1. Field of the Invention
The present invention relates to a structure for mounting a suspension member in a vehicle such as an automobile, and more particularly, to a structure for mounting a suspension member to a body of the vehicle.
2. Description of the Prior Art
As one of the supporting structures for the control arms in the suspension of a vehicle such as an automobile it is known to provide a suspension member in the form of an independent frame adapted to be supported from the vehicle body by vibration damping type connecting means and to mount the control arms to the suspension member. In order to improve the riding quality of the vehicle having such a suspension member, particularly to suppress the harshness, it is required that the mounting structure between the vehicle body and the suspension member has a relatively high flexibility in the longitudinal direction of the vehicle.
Such a flexibility between the vehicle body and the suspension member was provided in the conventional structure by the vibration damping means incorporated in the connecting means for mounting the suspension member to the vehicle body. Therefore, if the forces applied to the left side and right side wheels under driving or braking are different from one another, particularly when an anti-lock brake system or a traction control system is provided, the suspension member is rotated relative to the vehicle body as viewed from a top of the vehicle. Such a rotation of the suspension member causes toe changes of the wheels such as the tack-in or the like, and adversely affects the maneuvering stability of the vehicle.
Such a problem will still occur in a structure improved of the flexibility of the suspension member as described in, for example, Japanese Patent Publication No. 61-37152, in which the lateral frames of the suspension member are formed to have an open cross section so as to be relatively rigid against the lateral forces while relatively flexible for twisting under longitudinal forces. Therefore, the flexibility or rigidity of the vibration damping mount for the suspension member was conventionally determined in general under a compromise between the riding quality and the stability of the vehicle, and therefore the riding quality and the maneuvering stability were respectively not always very satisfactory.